I had debris in my anti siphon too. It is a 1.5" fitting at the fuel tank. I would not trust the shop saying they "fully" checked the fuel system.

I installed a permanent fuel gauge in-line just before the carb. This lets me see that I have fuel pressure and can help trouble shoot anything down line if needed.
The reason I suspect fuel delivery somewhere is power and rpm loss is only occurring under load. Unloaded, the demand is not as great and a partial blockage may be able to deliver enough fuel to not cause a problem.

Took the boat back to the lake. Now it only revs in neutral to a certain point then acts the same as in drive. Put new gas in with sea foam. I will try to post a video. The fuel pump seems louder than normal. Is it possible the fuel pump is working until it has to pump a lot of fuel at once?

Fuel pump supplies constant pressure - - do you have the correct pressure on fuel line to TBI - looks like fuel is not making it to TBI consistently....IMO - have you also checked the fuel pump intake screen?

__________________...A bad day water skiing still beats a good day at work...1995 Pro Star 205....

Looked at movie again...is that the fuel pump howling like that? On my TBI when I give it gas the flow of fuel increase...your seems to be dropping out and then the you run lean when the throttle body opens up... I am betting on a bad fuel pump - Napa carries them online... or the screen at the bottom of pump is fouled... CC2MC I believe just had the same problem. I cleaned mine out in 2011 - I was surprised I got any performance at all.

__________________...A bad day water skiing still beats a good day at work...1995 Pro Star 205....

Fuel pump supplies constant pressure - - do you have the correct pressure on fuel line to TBI - looks like fuel is not making it to TBI consistently....IMO - have you also checked the fuel pump intake screen?

After watching the video, I agree. Check fuel pressure. Can you pull codes from the ECU?

I had debris in my anti siphon too. It is a 1.5" fitting at the fuel tank. I would not trust the shop saying they "fully" checked the fuel system.

I installed a permanent fuel gauge in-line just before the carb. This lets me see that I have fuel pressure and can help trouble shoot anything down line if needed.
The reason I suspect fuel delivery somewhere is power and rpm loss is only occurring under load. Unloaded, the demand is not as great and a partial blockage may be able to deliver enough fuel to not cause a problem.

Bsloop - where did you get that guage? that's a pretty neat idea...

__________________...A bad day water skiing still beats a good day at work...1995 Pro Star 205....

The anti siphon valve is usually screwed onto the right angle fitting as it comes out of the gas tank headed forward toward the engine. It will usually be threaded on one end and barbed on the other to accept the fuel line. The fuel shut off valve sounds "aftermarket" and is probably not necessary, possibly a cause of the problem depending on the valve???

The pump changing sounds definitely sounds like an increasing restriction. Could be a hose getting soft and collapsing too. Our fuel lines are pre-ethanol so this may be taking its toll as well. As the link suggests a vacuum gauge may be your trouble shooting friend as well.

My anti-siphon restriction got progressively worse over the course of a season. When it started, I could run for 10min+ or longer then start losing power, then less time and less power. I threw carb rebuild (found a cracked float anyway), fuel pump etc at it til I finally got a vacuum gauge.http://www.harborfreight.com/fuel-pu...ter-93547.html